/*
 * Copyright (c) 2007, 2015, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied. See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
/*
 * Copyright (c) 2005, 2013, Oracle and/or its affiliates. All rights reserved.
 */
/*
 * $Id$
 */
package com.sun.org.apache.xml.internal.security.signature.reference;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;
import java.util.NoSuchElementException;
import org.w3c.dom.NamedNodeMap;
import org.w3c.dom.Node;

/**
 * A representation of a <code>ReferenceNodeSetData</code> type containing a node-set.
 * This is a subtype of NodeSetData that represents a dereferenced
 * same-document URI as the root of a subdocument. The main reason is
 * for efficiency and performance, as some transforms can operate
 * directly on the subdocument and there is no need to convert it
 * first to an XPath node-set.
 */
public class ReferenceSubTreeData implements ReferenceNodeSetData {

  private boolean excludeComments;
  private Node root;

  public ReferenceSubTreeData(Node root, boolean excludeComments) {
    this.root = root;
    this.excludeComments = excludeComments;
  }

  public Iterator<Node> iterator() {
    return new DelayedNodeIterator(root, excludeComments);
  }

  public Node getRoot() {
    return root;
  }

  public boolean excludeComments() {
    return excludeComments;
  }

  /**
   * This is an Iterator that contains a backing node-set that is
   * not populated until the caller first attempts to advance the iterator.
   */
  static class DelayedNodeIterator implements Iterator<Node> {

    private Node root;
    private List<Node> nodeSet;
    private ListIterator<Node> li;
    private boolean withComments;

    DelayedNodeIterator(Node root, boolean excludeComments) {
      this.root = root;
      this.withComments = !excludeComments;
    }

    public boolean hasNext() {
      if (nodeSet == null) {
        nodeSet = dereferenceSameDocumentURI(root);
        li = nodeSet.listIterator();
      }
      return li.hasNext();
    }

    public Node next() {
      if (nodeSet == null) {
        nodeSet = dereferenceSameDocumentURI(root);
        li = nodeSet.listIterator();
      }
      if (li.hasNext()) {
        return li.next();
      } else {
        throw new NoSuchElementException();
      }
    }

    public void remove() {
      throw new UnsupportedOperationException();
    }

    /**
     * Dereferences a same-document URI fragment.
     *
     * @param node the node (document or element) referenced by the URI fragment. If null, returns
     * an empty set.
     * @return a set of nodes (minus any comment nodes)
     */
    private List<Node> dereferenceSameDocumentURI(Node node) {
      List<Node> nodeSet = new ArrayList<Node>();
      if (node != null) {
        nodeSetMinusCommentNodes(node, nodeSet, null);
      }
      return nodeSet;
    }

    /**
     * Recursively traverses the subtree, and returns an XPath-equivalent
     * node-set of all nodes traversed, excluding any comment nodes,
     * if specified.
     *
     * @param node the node to traverse
     * @param nodeSet the set of nodes traversed so far
     * @param the previous sibling node
     */
    @SuppressWarnings("fallthrough")
    private void nodeSetMinusCommentNodes(Node node, List<Node> nodeSet,
        Node prevSibling) {
      switch (node.getNodeType()) {
        case Node.ELEMENT_NODE:
          nodeSet.add(node);
          NamedNodeMap attrs = node.getAttributes();
          if (attrs != null) {
            for (int i = 0, len = attrs.getLength(); i < len; i++) {
              nodeSet.add(attrs.item(i));
            }
          }
          Node pSibling = null;
          for (Node child = node.getFirstChild(); child != null;
              child = child.getNextSibling()) {
            nodeSetMinusCommentNodes(child, nodeSet, pSibling);
            pSibling = child;
          }
          break;
        case Node.DOCUMENT_NODE:
          pSibling = null;
          for (Node child = node.getFirstChild(); child != null;
              child = child.getNextSibling()) {
            nodeSetMinusCommentNodes(child, nodeSet, pSibling);
            pSibling = child;
          }
          break;
        case Node.TEXT_NODE:
        case Node.CDATA_SECTION_NODE:
          // emulate XPath which only returns the first node in
          // contiguous text/cdata nodes
          if (prevSibling != null &&
              (prevSibling.getNodeType() == Node.TEXT_NODE ||
                  prevSibling.getNodeType() == Node.CDATA_SECTION_NODE)) {
            return;
          }
          nodeSet.add(node);
          break;
        case Node.PROCESSING_INSTRUCTION_NODE:
          nodeSet.add(node);
          break;
        case Node.COMMENT_NODE:
          if (withComments) {
            nodeSet.add(node);
          }
      }
    }
  }
}
